3Com SuperStack 4 Configuration Manual page 201

Packet Filter
Packet filter is used to filter traffic. For example, the operation "deny" discards the
traffic that is matched with a traffic classification rule, while allowing other traffic
to pass through. With the complex traffic classification rules, the Switche enables
the filtering of various information carried in Layer 2 traffic to discard the useless,
unreliable or doubtful traffic, thereby enhancing the network security.
The two key steps of realizing the frame filtering are as follows.
1 Classify the ingress traffic according to the classification rule;
2 Filter the classified traffic, i.e. the "deny" operation, the default ACL operation.
Traffic Policing
To deliver better service with the limited network resources, QoS monitors the
traffic of the specific user on the ingress, so that it can make a better use of the
assigned resource.
Port traffic limit
The port traffic limit is the port-based traffic limit used for limiting the general
speed of packet output on the port.
Traffic Priority
The Ethernet Switch can deliver priority tag service for some special packets. The
tags include TOS, DSCP and 802.1p, etc., which can be used and defined in
different QoS modules.
Queue Scheduling
When congestion occurs, several packets will compete for the resources. The
queue scheduling algorithms are used to overcome the problem. Here
Strict-Priority Queue (SP) queue scheduling algorithm is introduced.
QoS Configuration 213